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Updated: 2015 AUG 20, 06:29 UT
Event Rank : 61
(The event Rank is a measure of the likelihood of observing an event, and is equal to the probability of at least one successful observation by a team of two observers spaced 1/8 path width just inside opposite sides of the predicted path. An event rank of 100 indicates that the prediction is expected to be very accurate).
THE UPDATED PATH
Note: The duration given in the line below is the interval during which the occultation shadow sweeps across the Earth - please see the minute markers on the map to determine the approximate time for your location.
On 2015 Sep 19 UT, the 75 km diameter asteroid (907) Rhoda will occult a 12.4 mag star in the constellation Sagittarius for observers along a path across Australia, from Wilsons Promontory across Victoria to Mildura, including Melbourne, across north-eastern South Australia and The Northern Territory to Darwin. May include the north-eastern corner of Tasmania.
In the case of an occultation, the combined light of the asteroid and the star will drop by 2.9 mag to 15.3 mag (the magnitude of the asteroid) for at most 8.5 seconds.
This update is based on UNSO/Flagstaff astrometry for the asteroid kindly provided by Alice Monet, historical astrometry from the MPC files (via AstDys), and the following catalogs for the star position: UCAC.
Additional details of this and other events are available at Steve Preston's website at http://www.asteroidoccultation.com/
EVENT DETAILS SUMMARY :Important Note regarding Accuracy:
The uncertainty interval in path widths given above (and shown as a 1-sigma uncertainty ellipse on the plot) refers to RMS deviation and is applied as a +/- range. In other words, a path uncertainty of 1.0 path widths means that the actual center of the asteroid's shadow path should fall within plus or minus 1 path width of the plotted path center. However path errors larger than 1 sigma have been observed so observers should be alert for primary occultations within plus or minus 3 sigma of the updated path.
Further, almost all asteroidal satellites discovered so far have been found within 10 diameters of the asteroid (since this distance is deep enough within the gravitational well to be stable over long timescales). Therefore, if monitoring for secondary events, observing out to about 10 path-widths either side of the predicted track remains worthwhile.
We therefore recommend that you monitor for events if your observing location is up to +/- 10 path-widths from the predicted track. If not monitoring for occultations by secondary bodies you should observe from locations within 3 sigma of the nominal path.
In terms of time, the predictions are now usually accurate to about +/- 0.3 minute so you should be most attentive during the predicted minute of the event. However if intending to catch a potential satellite occultation you should start observing at least 10 times the predicted central duration before the predicted closest approach time for your location, and continue for a similar period afterwards.
Centre Star Star Sun Path Limits Error Limits
E. Longitude Latitude U.T. Alt Az Alt Limit 1 Limit 2 Limit 3 Limit 4
o ' " o ' " h m s o o o o ' " o ' " o ' " o ' "
Longitude Longitude Longitude Longitude
128 52 26 - 5 0 0 12 21 57 50 187 -46 129 14 53 128 30 3 130 0 23 127 44 59
129 10 54 - 6 0 0 12 21 46 51 188 -46 129 33 25 128 48 26 130 19 5 128 3 13
129 29 49 - 7 0 0 12 21 36 52 188 -46 129 52 25 129 7 16 130 38 15 128 21 53
129 49 13 - 8 0 0 12 21 25 53 189 -46 130 11 55 129 26 34 130 57 56 128 41 0
130 9 6 - 9 0 0 12 21 14 54 189 -47 130 31 54 129 46 22 131 18 8 129 0 36
130 29 30 -10 0 0 12 21 3 55 190 -47 130 52 24 130 6 39 131 38 53 129 20 39
130 50 25 -11 0 0 12 20 51 56 191 -47 131 13 27 130 27 27 132 0 10 129 41 13
131 11 53 -12 0 0 12 20 40 57 191 -47 131 35 3 130 48 47 132 22 2 130 2 18
131 33 54 -13 0 0 12 20 28 58 192 -47 131 57 13 131 10 40 132 44 30 130 23 54
131 56 31 -14 0 0 12 20 17 59 193 -47 132 19 58 131 33 7 133 7 34 130 46 4
132 19 44 -15 0 0 12 20 5 59 194 -47 132 43 21 131 56 11 133 31 17 131 8 48
132 43 35 -16 0 0 12 19 53 60 194 -47 133 7 23 132 19 51 133 55 40 131 32 8
133 8 5 -17 0 0 12 19 40 61 195 -47 133 32 4 132 44 10 134 20 45 131 56 5
133 33 16 -18 0 0 12 19 28 62 196 -47 133 57 27 133 9 9 134 46 32 132 20 41
133 59 10 -19 0 0 12 19 16 63 198 -47 134 23 34 133 34 51 135 13 5 132 45 57
134 25 48 -20 0 0 12 19 3 64 199 -47 134 50 26 134 1 16 135 40 25 133 11 55
134 53 13 -21 0 0 12 18 50 65 200 -47 135 18 5 134 28 27 136 8 34 133 38 38
135 21 27 -22 0 0 12 18 38 65 201 -47 135 46 34 134 56 25 136 37 35 134 6 7
135 50 32 -23 0 0 12 18 25 66 203 -47 136 15 56 135 25 14 137 7 30 134 34 24
136 20 31 -24 0 0 12 18 12 67 204 -47 136 46 12 135 54 56 137 38 22 135 3 32
136 51 26 -25 0 0 12 17 58 68 206 -47 137 17 26 136 25 33 138 10 14 135 33 33
Latitude Latitude Latitude Latitude
137 0 0 -25 16 17 12 17 55 68 207 -47 -24 26 45 -26 5 20 -22 45 7 -27 43 5
138 0 0 -27 6 37 12 17 30 69 210 -47 -26 18 51 -27 53 58 -24 40 57 -29 28 25
139 0 0 -28 50 40 12 17 6 70 214 -47 -28 4 30 -29 36 27 -26 30 1 -31 7 52
140 0 0 -30 28 53 12 16 44 71 218 -47 -29 44 12 -31 13 14 -28 12 50 -32 41 50
141 0 0 -32 1 42 12 16 22 71 223 -46 -31 18 24 -32 44 43 -29 49 54 -34 10 43
142 0 0 -33 29 31 12 16 1 72 227 -46 -32 47 28 -34 11 16 -31 21 38 -35 34 50
143 0 0 -34 52 38 12 15 41 72 231 -46 -34 11 47 -35 33 15 -32 48 24 -36 54 32
144 0 0 -36 11 24 12 15 22 72 235 -45 -35 31 39 -36 50 56 -34 10 35 -38 10 6
145 0 0 -37 26 6 12 15 4 72 239 -45 -36 47 22 -38 4 37 -35 28 27 -39 21 48
146 0 0 -38 36 59 12 14 47 72 243 -45 -37 59 14 -39 14 33 -36 42 19 -40 29 51
147 0 0 -39 44 18 12 14 30 72 247 -44 -39 7 27 -40 20 58 -37 52 25 -41 34 30
148 0 0 -40 48 16 12 14 14 72 250 -44 -40 12 16 -41 24 5 -38 59 1 -42 35 58
149 0 0 -41 49 5 12 13 58 72 253 -43 -41 13 54 -42 24 7 -40 2 18 -43 34 25
150 0 0 -42 46 57 12 13 43 71 256 -43 -42 12 31 -43 21 14 -41 2 30 -44 30 2
151 0 0 -43 42 2 12 13 29 71 258 -43 -43 8 19 -44 15 36 -41 59 47 -45 23 0
152 0 0 -44 34 29 12 13 15 70 261 -42 -44 1 28 -45 7 23 -42 54 20 -46 13 26
153 0 0 -45 24 28 12 13 2 70 262 -42 -44 52 5 -45 56 43 -43 46 17 -47 1 31
154 0 0 -46 12 6 12 12 49 69 264 -42 -45 40 20 -46 43 45 -44 35 48 -47 47 20
Uncertainty in time = +/- 11 secs
Prediction of 2015 Aug 20.0
Use these links for further information:
[Planetary Occultations]
[Using the Predictions]
[Observing Details]
[Timing Details]
[Reporting Details]
[Report Form]
[Asteroid Occultation Results]
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